D-3-Hydroxybutyrate (HB) is a primary metabolite in diabetic keto-acidosis, alcoholism, or starvation. The untreated ketoacidosis can result in coma or death. The current test for ketosis measures only acetoacetate, which is a minor ketoacid and is unstable. Therefore, the test sometimes leads to an error in diagnosis. A simple, quick strip-test for blood HB measurements would be a valuable tool for both diagnosis and management of ketosis. Phase I research has clearly established that a stable strip-test can be developed using GDS' thermostable D-3-Hydroxybutyrate dehydrogenase. The indicator selected produces an excellent visual color discrimination which is proportional to the HB concentration in serum. The objective of Phase II program is to (1) convert the present serum test into a whole blood test, (2) increase the test's stability to more than one year at room temperature, (3) produce strips on a pilot scale, and (4) perform extensive clinical evaluation with the methodology. The program is attractive as it offers, for the first time, an opportunity for providing a simple and offers, for the first time, an opportunity for providing a simple and accurate test for ketosis or ketoacidosis that can be done "on-site", such as in physicians' offices, emergency rooms, or at home during insulin therapy.